Sunday, May 22, 2011

What is PDD-NOS?

ResearchBlogging.orgSome cases of autism are obvious. Anyone who knew anything about autism would agree that the child or adult in question was autistic. Other cases are less clear cut. Indeed, the term “autism spectrum” implies the existence of a continuum that fades gradually into what we think of as the “normal” population.

Somewhere a line has to be drawn and where exactly we choose to draw that line defines what we mean by autism. It determines who is eligible to take part in autism-related research and this in turn influences the development of theories of autism. Eventually, this feeds back to our evolving definitions and cut-offs for autism. Most importantly when it comes to immediate real-world consequences, the diagnostic boundaries specify who is labeled “autistic” and, ultimately, who gains access to interventions and support.

In the absence of reliable biological markers or break points in the continuum, diagnoses are made by checklist. Tick enough boxes and you get a diagnosis of “autistic disorder” or “Asperger’s disorder”. Tick fewer boxes or the ‘wrong’ combination of boxes and you’re not considered autistic. You may, however, qualify for the mysterious diagnosis of PDD-NOS - “Pervasive Developmental Disorder – Not Otherwise Specified”.

Defining PDD-NOS

“Pervasive Developmental Disorder” is an umbrella term covering five diagnoses:
  1. Autistic disorder
  2. Asperger's syndrome
  3. Rett syndrome
  4. Childhood disintegrative disorder
  5. PDD-NOS
    As the name suggests, PDD-NOS is generally thought of as a residual category for people who have a pervasive developmental disorder but don't quite fit into the other more specific categories. However, this all gets a bit circular because "pervasive developmental disorder" is defined only in terms of its constituent diagnoses. You've got a pervasive developmental disorder if you have any of the five diagnoses above (including PDD-NOS), and you've got PDD-NOS if you don't have the other four.

    In practice, PDD-NOS is defined along the same lines as autism but with less strict cut-offs. Current autism diagnostic criteria require evidence of difficulties in each of three 'domains' - the famous autistic triad of:
    • social impairments
    • communication impairments
    • repetitive and stereotyped behaviours (RSBs for short).
      The 1994 version of the diagnostic rules allowed a PDD-NOS diagnosis to be given to anyone with significant impairment in any one of the three domains.

      However, the most recent revision, published in 2000, is much more restrictive. PDD-NOS is currently defined as:
      “a severe and persistent impairment in the development of reciprocal social interaction associated with impairment in either verbal or nonverbal communication skills or with the presence of stereotyped behavior, interests and activities”
      In other words, there has to be evidence of impairment in exactly two domains and one of these has to be the social domain.

      Confused? You ought to be.

      PDD-NOS and DSM 5

      In 2013, the diagnostic rules are set to change yet again. One of the proposals for the new set of rules, codenamed DSM 5, is to do away with the current distinction between autism, Asperger's, and PDD-NOS, replacing them with a single super-category of "Autism Spectrum Disorders". 
        While there has been heated debate about the abolition of the Asperger's diagnosis, there appears to be little opposition to the demise of PDD-NOS. It's not hard to see why. The term itself is unwieldy, suggesting diagnostic uncertainty. And there's no real sense of a PDD-NOS identity as there is for Asperger syndrome.

        An important question, however, is what will happen to people who would currently be diagnosed with PDD-NOS? In a study, published recently in the journal, Autism Research, William Mandy and colleagues at University College London set out to address precisely this question.

        Specifying PDD-NOS

        The study centred on the Developmental, Dimensional and Diagnostic Interview (known as the 3Di), a semi-structured interview, which provides scales for the three autism domains (social, communication, RSBs) as well as a number of other clinically relevant scales such as auditory sensitivity, motor impairment, and sleep difficulties.

        The 3Di was administered to parents of 256 children who had been referred for assessment. Based on the parents' responses, the researchers were able to identify 66 kids who met criteria for PDD-NOS according to the current rules. In other words, these kids were above the diagnostic threshold on the social scale and either the communication or the RSB scale. The remaining kids in their sample were above the threshold on all three scales and so were diagnosed with autistic disorder or Asperger’s disorder (depending on their history of language development).

        The graph below shows the scores of the kids in the three diagnostic groups on each of the three main scales. Compared with children meeting criteria for autistic disorder or Asperger's disorder, the kids with PDD-NOS on average had lower scores (less impairment) on all three diagnostic scales. They also scored lower on the scales for auditory sensitivity, visuo-spatial impairment, and feeding difficulties (not shown in the graph).

        The PDD-NOS group (on the right) showed much lower levels of Repetitive Stereotyped Behaviours (Grey Bars) than kids with Autistic Disorder or Asperger's.
        Thanks to William Mandy for recreating the graph.

        As you can see in the far right column, group differences were particularly marked on the RSB scale. Indeed, the authors found that only two of the 66 PDD-NOS kids had clinically significant RSBs and both of these children were very close to also meeting the communication criterion, which would have given them a full autism diagnosis. The remaining 64 PDD-NOS kids fell well short of criteria for RSBs and achieved their PDD-NOS diagnosis by virtue of having both social and communication difficulties.

        The authors acknowledge that this isn't a huge sample and that kids weren't selected at random from the community so it might not give a totally accurate picture of the prevalence of the different diagnostic categories. However, their results suggest that what we currently term PDD-NOS should not be thought of as simply a milder form of autism. Nor is it, as the name suggests, merely a rag-bag miscellaneous category for kids whose difficulties can’t quite be pinned down. Rather, the PDD-NOS label appears to broadly correspond to those individuals facing social and communication difficulties in the absence of the RSBs that characterize autism and Asperger’s.

        Implications for DSM 5

        As Mandy et al. point out, their findings suggest a potential unforeseen consequence of the proposed changes to diagnostic criteria in DSM 5.

        To receive a diagnosis of "Autism Spectrum Disorder" (which is supposed to replace autism, Asperger's and PDD-NOS), an individual will have to show evidence of both:
        • social and communication impairment (these two domains will be merged)
        • repetitive and stereotyped behaviors (RSBs)
          Under these rules, 64 of the 66 children in the PDD-NOS group would not meet the criteria for Autism Spectrum Disorder. To the extent that Mandy et al.'s data are at all representative, this suggests that the overwhelming majority of people who currently meet criteria for PDD-NOS would not be considered autistic under DSM 5 and may not receive any form of diagnosis.

          There is certainly a case to be made that children are being over-diagnosed and that the boundaries for autism-related disorders should be brought in. However, there is also a real danger that individuals with severe social and communication difficulties would be excluded from support and interventions designed to improve their social and communication skills. All because they don’t also have RSBs.

          What is autism?

          Although the study focused on PDD-NOS, it also raises some more philosophical questions about what we actually mean by "autism" or "autism spectrum disorders". In particular, how do we determine what counts as a defining feature of autism?

          Up until the early 1970s, language impairment was seen as one of the major defining features of autism. Indeed, researchers such as Michael Rutter argued that autism was essentially a severe form of language impairment. This theory was abandoned, however, when it became clear that there were some individuals who had the social impairments associated with autism, despite having very good language skills. Gradually, the diagnostic criteria were relaxed and today language impairment is no longer considered a necessary criterion.

          Mandy et al.'s study seems to present an analogous situation with respect to repetitive and stereotyped behaviours. As with language impairment, RSBs have long been considered a defining feature of autism. And, as with language impairment, it now appears to be the case that a substantial group of individuals exhibit social impairments without exhibiting RSBs. This begs the question of why RSBs should continue to be considered a defining characteristic of autism when language impairment is not.

          Thinking outside the diagnostic box

          In essence, autism is whatever we say it is. Although we might like to think of it as a natural kind, an objectively discrete entity that falls out of nature, we're essentially just taking a multi-dimensional cookie cutter to the human population. Given our current state of ignorance, there is little alternative to this approach to diagnosis at this time. But for researchers, there's no obligation to be restricted by the prevailing diagnostic boxes in our quest to understand autism's place in the human spectrum.

          Update [06/06/11]

          In a new paper, Prof Francesca HappĂ© from the DSM 5 working group has addressed the Mandy paper and its implications for PDD-NOS. She suggests that most PDD-NOS individuals who don't meet DSM 5 criteria for ASD will fall under the new category of Social Communication Impairment. For more details, see my new post here.


          Mandy W, Charman T, Gilmour J, & Skuse D (2011). Toward specifying pervasive developmental disorder-not otherwise specified. Autism research : official journal of the International Society for Autism Research, 4 (2), 121-31 PMID: 21298812

          Related posts

          Exactly how many ways are there to get an autism diagnosis?

          Further reading:

          Francesca Happe: Why fold Asperger syndrome into autism spectrum disorder in DSM 5?

          John Elder Robison: What's the difference between Asperger's, autism, and PDD-NOS?

          Dorothy Bishop: What's in a name?

          Steven Hyman: Diagnosing the DSM: Diagnostic classification needs fundamental reform


          1. Thanks for this very thoughtful analysis of the current diagnostic issues in Autism Spectrum Disorders. One further problem I see is that we don't have very good behavioural tests - and therefore probably also not very good interview questions - about the three classes of diagnostic criteria. Here is a question: could RSB be present but invisible if we include not only motor behaviour but also repetitive stereotyped thoughts. For instance, an autistic individual may have learned not to talk about such thoughts. This doesn't mean they are not present. Still, it is very fascinating that one subgroup of the Autism spectrum does not show RSB when other subgroups do - at least in their parents' considered opinion.

          2. Interesting that Medicine has kept many of these "general" categories akin to PDD NOS, such as "irritable bowel" in G.I. or "Focal Dystonia" in neurology, and so forth. The big problem for people are "symptoms" that interfere greatly with their lives, even if we don't understand them. To simply discard large groups of people with serious life interfering symptoms is a problem. Isn't it?

          3. Hi Uta. That's a great question. Interesting too in the light of recent talks I've seen highlighting the overlap between autism and OCD, although I guess that's diagnosed in terms of obsessive behaviour (even if it's driven by obsessive thoughts).

            In a way, I suppose, it speaks to your self-confessed obsession with cognitive mechanisms in autism.


            The interesting question then is whether people with social communication problems but without RSBs nevertheless have the executive difficulties that are thought to underlie RSBs in autism.

            The alternative is that these individuals really do have social communication difficulties in the absence of repetitive stereotyped behaviours or thought processes. In that case, the interesting question would then be whether their social interaction difficulties were qualitatively similar to those of people with RSBs.

            For what it's worth, my view is that until we have convincing answers to these questions, the best approach diagnostically would be to define autism / ASD purely in terms of social interaction difficulties. However, I don't pretend to be an expert on these matters so I'd be really interested to know other people's thoughts.

            1. So odd to enter a nearly three old conversation. But as a 49 year old just discovering that PDD-NOS exists and that both myself, my husband, and my two children have it, I am uninformed enough to still be using my own anecdotal experience as the main mechanism to sift through what I am learning. As such, I find that defining anything based only on behavior is tremendously misleading as it can only be judged by those on the "outside" of the system. From the inside of the system, whether anyone can see the behavior or not, the difficulties exist within thought processes. And this creates the anxiety, depression, and PTSD. The thoughts are what matters. I have clearly learned to "behave" the way people expect - to some degree (which isn't much different than what any child must learn). We all learn to wear masks, as best we can. The amount of stress required to maintain the mask is excruciating. The lack of forgiveness in the population when the mask drops accidentally or because we are tired creates the pain. There are many times when I simply decide not to care, because I just want to be me and be accepted as such (rarely works). From the "outside", this would appear perhaps as if the system has no control. But the system does have control, if it can only muster the super-human strength to do so, and in so doing, deny their own particular form of humanity. It is the thoughts that also need addressing, if the outside world is to define us. Not just the behavior that the outside world finds offensive and off-putting. The effort to learn, control, and consistently think and repeat the "behavior" that is appropriate to the outside world does not come naturally, must be masked, and creates side-effects that are damaging. The thoughts and behaviors to the ASD are damaging. Well, that would be if we lived in a world that could tolerate differently-abled people.

          4. Thanks for the comment Larry.

            Mandy et al. actually make the following statement, which did surprise me:

            "In recent epidemiological studies PDD-NOS has been shown to be the most common PDD, with approximately double the prevalence of AD [Baird et al., 2006; Chakrabarti & Fombonne, 2005]"

            Part of that could be down to the older looser criteria for PDD-NOS and part to misdiagnosis (ie not applying the criteria 'by the book'). But it does still suggest that there are a lot of people out there who don't fit neatly into existing diagnostic boxes.

            For more on these issues, I'd highly recommend the "Diagnosing the DSM" I linked to under Further Reading.

          5. This is a very nice point:

            "The alternative is that these individuals really do have social communication difficulties in the absence of repetitive stereotyped behaviours or thought processes. In that case, the interesting question would then be whether their social interaction difficulties were qualitatively similar to those of people with RSBs."

            I fear that diagnosing autism solely by impairments in social interaction could result in an even more heterogeneous group. There are just too many ways to have a social impairment. We need to specify what particular kind of social impairment is characteristic of autism. Or else, people who are shy, people who don't get on with anybody, bullies, loners, bores etc might all fall into such a category.

          6. Uta, I absolutely agree that there is a need to specify the nature of social impairment that we're talking about. The question is whether the current requirement for co-occurring RSBs helps restrict that heterogeneity in any useful way.

            I share your intuition that the categories of people you mentioned should not be considered autistic. If the social interaction component of diagnostic protocols can't differentiate between them, this means one of two things: either our intuitions are wrong or the diagnostic protocols aren't very good.

          7. John, you correctly note that:

            'I fear that diagnosing autism solely by impairments in social interaction could result in an even more heterogeneous group. There are just too many ways to have a social impairment. We need to specify what particular kind of social impairment is characteristic of autism. Or else, people who are shy, people who don't get on with anybody, bullies, loners, bores etc might all fall into such a category'.

            DSM-III (1980) encoded Kanner's definition of a 'pervasive lack of responsiveness to other people - autism' as the core cognitive disability in autism.

            Prior to the publication of DSM-III-R (1987) and DSM-IV (1994) there was a great deal of debate and argument over diagnostic issues in autism. Eric Schopler and Michael Rutter, the co-editors of the Journal of Autism and Developmental Disorders both recognized that there was a large group of children who did not meet diagnostic criteria for DSM-III (1980) autism but who share one or another 'autistic-like' symptom. It was felt that these children were not being recognized and were falling through the cracks and they were not being given the opportunity for early intervention programs and special education programs.

            By 1994, Kanner's definition was completly removed from all diagnostic schemes by DSM-IV (1994) and ICD-10 (1994) and the 'Gold Standard diagnostic tools (ADI, ADOS etc) based on DMS-IV and ICD-10 and replaced by the vague, ambigous and subjective 'qualitative impairments in social reciprocity' which as you state could be inclusive of 'people who are shy, people who don't get on with anybody, bullies, loners, bores etc might all fall into such a category'.

            I'll give just one such example, Fragile X and co-occuring autism. Prior to 1994 Fragile X and co-occuring autism was thought to be relatively rare The latest reports on Fragile X and co-occuring autism using DSM-IV-TR (2000) criteria has reported the highest rates of Fragile X with co-occuring autism with Hagerman reporting that 30% of Fragile X males meet diagnostic criteria for Autistic Disorder and a further 30% meeting diagnostic criteria for PDD/NOS.

            Several research groups have questioned this finding and have noted that the social impairments in Fragile X boys is not a pervasive lack of responsiveness to other people, but rather their social difficulties are that of shyness and social anxiety.

            No one has the complete answer for defining exactly what autism is but any new diagnostic scheme that may cause a large group of children to 'fall through the cracks' and be denied access to early invtervention and special education should be objected to.

            Diagnostic schemes for autism has become, in my view, an instrument for social policy that I fully support.

          8. Jon;

            One always has to consider who are the members of the the APA's working group on the PDD's charged with creating diagnostic criteria for the DSM-V. They are primarily mostly behavioral geneticists who ascribe to a conceptual model of autism as being dimensional with autism as the tail end of a distribution of autistic traits that extend very broadly throughout the general population.

            It would appear that the working group is headed towards a set of diagnostic criteria in line with the concept of autism being dimensional.

            At the IMFAR conference in San Diego last week the California Autism Twin Study group presented their latest results. They found that autism is not the tail end of a normal distribution of autistic-like traits but is a discrete clinical entity (categorical).
            They also reported that severity of autism is not heritable


            The debate and argumant about autism definition has been going on for decades with no one able to define exactly what autism is and what it is not. Debate and argument over whether autism is a discrete category or if it is a dimensional condition has also been going around in crcles for decades.

            We can only hope that any new DSM-V will not lose children who would benefit from being given a diagnostic label that would be a passort to early intervention and special education.

          9. As a descriptive term denoting significant impairments in social interaction, ‘autism’ is very useful. Using exactly the same term to denote a hypothetical developmental disorder or disorders is, in my opinion, highly misleading. Although it’s likely that children who could be described as autistic have a biological cause or causes for their behaviours, use of ‘autism’ as a diagnosis carries with it the implication that all children to whom the descriptive term applies have the same, or related, biological cause(s) for their behaviours. They might, but we don’t know that they do, and shouldn’t assume it.

            Kanner saw impairments in social interaction as the central characteristic of the children in his sample because, from the psychodynamic perspective prevalent at the time, affect was considered foundational to development. Kanner attributed the difficulty some of the children had in suckling and their speech impairment to a disturbance in affect even though an equally plausible explanation is that sensory processing and/or problems with motor control led to both. There’s no doubt that all Kanner’s children showed impaired social interaction, but they also showed a diverse range of other developmental abnormalities that he cheerfully sidelines.

            I can see that identifying similarities between children could help to isolate causes, but identifying similarities using constructs at a high level of complexity (social interaction, communication, RSB) seems a rather strange way to go about it, because so many variables are involved in each construct.

            In addition, defining the signs and symptoms of putative medical conditions solely in behavioural terms marginalizes signs and symptoms with a much lower level of complexity that are commonly found in autistic children – such as sensory, musculoskeletal and digestive abnormalities. Lower-level characteristics could provide more tractable clues to underlying causes. It was investigating a low-level somatic characteristic – urine that smelled musty - that led to the discovery of PKU, not investigating the high-level characteristic mental retardation.

            Attempting to identify the causes of a cluster of developmental abnormalities by framing them solely in behavioural terms and then framing those behaviours in terms of highly complex constructs appears to me to be an approach to that is conceptually flawed.

            Back to the drawing board, I think.

          10. Wow. Thanks for all the brilliant comments. Volcano permitting, I'm just about to get on a plane and I'll respond properly when I get a chance. In the meantime, talk amongst yourselves!

            Sue - you may be interested in this, just out:


          11. Thanks for the link. All the best with the volcano!

          12. I would disagree with Sue Gerrards minimizing the magnitude of Kanner's contribution.

            It is true that in 1940's in the field of psychiatry human behavior was thought to be psychodynamic and that aberrant behavior in children was thought to be the consequnce of the failure of mother-baby interactions (refrigerator mother). Kanner never held that view. In fact he later wrote many articles in defense of the mothers.

            In 1965 he wrote an article on the history of psyhiatry's response to his 1943 article that is as relevant today as it was in 1965:


            Among his observations was the following:

            'This sage advice was not heeded by many authors. While the majority of the Europeans were satisfied with a sharp delineation of infantile autism as an illness sui generis, there was a tendency in this country to view it as a developmental anomaly ascribed exclusively to maternal emotional determinants. Moreover, it became a habit to dilute the original concept of infantile autism by diagnosing it in many disparate conditions which show one or another isolated symptom found as a part feature of the overall syndrome. Almost overnight, the country seemed to be populated by a multitude of autistic children, and somehow this trend became noticeable overseas as well. Mentally defective children who displayed bizarre behavior were promptly labeled autistic and, in accordance with preconceived notions, both parents were urged to undergo protracted psychotherapy in addition to treatment directed toward the defective child's own supposedly underlying emotional problem.

            He further observed:

            'To complicate things further, Crewel, in the hope of avoiding confusion between true autism and other conditions with autistic-like features, suggested the term pseudo-autism for the latter. Even this term came to be employed haphazardly, and conditions variously described as hospitalism, anaclitic depression, and separation anxiety were put under the heading of pseudo-autism'.

            In the 1990's Rutter et al. studied the long term outcomes of Romanian orphans who were place in horrendous Romanian orphanages where they suffered from extreme social isolation with about 10% of the orphans meeting criteria for autism using gold standard diagnostic tools.

            Rutter did observe that the autistic symptoms in these children were similar in many ways to autism but they were also many dissimilarities to 'ordinary' autism.

            Rutter gave these children the label of 'Quasi-Autism' similar to Crewe's label of 'Pseudo-Autism'.

          13. @ Anonymous: I wasn't minimizing the magnitude of Kanner's contribution at all - quite the opposite. I was suggesting that out of the wide array of developmental abnormalities shown by the children in his sample, Kanner selected disturbances of affect as the core feature because affect was central to the theoretical model most widely used to account for behaviour at the time. And that later researchers have tended to develop Kanner's thesis, rather than look at the array of abnormalities - behavioural and somatic - seen in the individual child.

            With regard to the mother-child interaction, Kanner refers to the 'innate inability to form the usual, biologically provided affective contact with people' - so it's pretty clear that at the time of writing he was thinking about a biological factor in the child, rather than in the mother-child interaction, though wisely he keeps his options open.

          14. I'd like to pick up on the point made by Larry Welkowitz about diagnosis and functional impairment.

            Putting aside theoretical concerns for a moment, and simply thinking about the clinical utility of ASD diagnoses the question is: Do people who meet criteria for PDD-NOS have distinct needs compared to people with full autism? If the answer is yes, then there is a practical justification for them having a distinct label to communicate their specific needs. On the other hand, if the needs of people with PDD-NOS are similar in type and degree to those with the full autism triad, it becomes harder to justify giving them a different diagnosis, or excluding them from the autism spectrum.

            Our clinical experience is that children with PDD-NOS (i.e. mainly individuals with severe autistic social-communication difficulties, but without high levels of repetitive and stereotyped behaviours) are similar to those with a full autism diagnosis in terms of their functional impairment.

            We recently took a look at some data from our clinic to test this impression more formally. We used regression models to look at how IQ and autism triad symptoms predicted scores on the Vinelands Adaptive Behavior Scale - Second Edition (VABS-II) in a sample of 70 consecutive referrals. Interestingly IQ and reciprocal social interaction independently predicted VABS-II scores. Communication and repetitive stereotyped behaviour did not.

            I stress that these are unpublished findings - they have not yet been submitted for peer review. However, they do offer some support for the notion that it is reciprocal social interaction that, at least from a clinical perspective, is at the core of the autism syndrome. On that basis, you could argue that it is hard to justify excluding individuals from the autism spectrum because they do not have repetitive and stereotyped behaviours.

          15. Jon;

            The dispute between those who see 'autism' as being dimensional with autism as the the tail end of a continous distribution of 'autistic-like traits' that extend very broadly, not only within the families, but throughout the general population and those who see autism as being categorical may be partly or entirely largely resolved by Michael Rutter's two-hit hypothesis which states that the genes underlying the broad autism phenotype are not the same as the genetic and environmental factors involved in the transition to the handicapping disorder.


            The seperate mechanism involved in 'autistic-like' traits may very well be dimensional. Plomin's group has recruited thousands of twins from the Twins Early Developmental Study (TEDS)and using questionnaires have stated that 'about 10%' of all children demonstrate 'extreme autistic-like traits'. While cutoffs for what is and is not an autistic-like trait may be arbitrary lowering the cutoff score would extend the prevelance of general population even beyond the 10% cutoff used by Plomin's group that defined extreme autistic-like traits.

            The recent twin study presented last week at the IMFAR conference has also found that severity of autism is not heritable and is not the tail end of a continous distribution of autistic like traits in the general population.

            The second seperate mechanism, the disruption of early brain development associated with many complex genetic and environmental factors that induce the neuroanatomical alterations involved in the transition to the handicapping disorder.

            It is the differences in brain structure that distuinguishes affected from unaffected family members who may very well share the genetic influences underlying the broad autism phenotype but it is brain structure and functionig that makes 'autism' a discrete categorical entity.

          16. We've arrived safely back in Australia. I must say it's been great fun reading the comments while waiting for connections. Thanks to all for their fascinating contributions. It's extremely gratifying that my little blogpost can generate such a rich discussion.

            Special thanks to Will Mandy - it's brilliant when the authors of the study can join in the discussion, particularly when they bring new data!

            I'm in complete agreement about the need to separate out clinical and theoretical considerations. The diagnostic criteria are deliberately atheoretical, aiming to identify individuals with broadly similar behaviours and clinical needs regardless of underlying cause. Will's data (old and new) are extremely informative here in terms of where we should be drawing the boundaries for the autism group.

            Problems arise when people take the diagnostic criteria too seriously and conclude that "autism vs not-autism" is the only relevant unit of individual difference for research into the causes of autism. This was Sue's point too.

            In the future, we may end up with diagnostic tools that allow us to identify clinical groups that map on well to underlying mechanisms and allow more individualised intervention strategies based upon this knowledge. But we'll only arrive at that goal if we acknowledge the fact that the current diagnostic groupings almost certainly don't map onto causes and design our research studies accordingly.

          17. Am I to understand that if a child has an intellectual disability, he will no long be autistic?

            Rose Walker Georgia USA

          18. Hi Rose

            I haven't heard anything to suggest that having an intellectual disability would preclude an autism diagnosis. That would exclude a large proportion of the current autism population, primarily those in most need of support. So I can't imagine why anyone would ever suggest that.

            If something in the original post wasn't clear, let me know - it's useful feedback for me :)

            Cheers, Jon

          19. No sir, I looked at the write up and must say I'm relieved that my son will no longer be considered autistic with his PDD-NOS label, if I understand correctly.( He was under the shadow of the autism spectrum umbrella.) Thanks...because I, with my teaching background, see him as dyslexic (in math and writing.) People seem to understand dyslexia a bit more, and realize it is beyond the child's abilities to remediate, that they must learn coping strategies. I don't think it has the stigma of mental illness that autism does. (You know, being a puzzle and all...pffftttt!)I always thought it should be Pretty Darn Disagreeable, anyhow, but I'm a simpleton.

            That notion came from a man who noted the disclaimer "not accounted for by general developmental delays"

            He's a lawyer, so he's into precise wording.

            Rose in Georgia

          20. Rose: I've just had a look through that link and, while I'm no authority on these matters, I think the poster has misinterpreted the proposed new guidelines. That said, it's easy to see why he reached that conclusion - particularly if he's a lawyer!

            The 'offending' phrase in the new guidelines is this:

            "Persistent deficits in social communication and social interaction not accounted for by general developmental delays"

            I would translate it something like this:

            "Social communication deficits that are more severe than those exhibited by non-autistic individuals with comparable levels of intellectual disability".

            In other words, it's fairly common for people with intellectual disability to also have difficulties with social interactions (because navigating through the social world is an intellectually demanding activity). The guidelines are trying to say that ASD is more than that just intellectual disability, but not excluding the possibility that someone can have both.

          21. Thanks, I'll let him know. He does have a severely autistic son and is pretty sensitive towards those on the lower end of the spectrum. He feels those of higher intellectual ability (unto genius) do not compare, and "his children" receive the leftover scraps of current research, while higher functioning people labeled autistic are studied copiously, even Kanners.

            I think he would appreciate a more organic, biological basis of autism rather than the "navel gazing" of Aspergians, who may live indepedently. Having worked with kids with major disabilities, in comparison to my son...I can see where he is coming from. Yet the developmental trajectory is so similar in each, that something good will come of it.

            Sorry, I do tend to get it out there and over with.

            Rose in Georgia

          22. Anonymous Rose:

            I think there's a really important issue here. It's not so much that severely (for want of a better word) autistic people are excluded from research altogether but that they are excluded from research that requires their compliance - basically any kind of cognitive or functional imaging research.

            As a result, we as researchers end up extrapolating what we know (or think we know) about cognition and brain activity in the "high functioning" / Asperger's end of the spectrum and just assuming that any problems affecting more severely autistic people are going to be similar but just more severe. It may be a reasonable assumption in some situations but it's an assumption nonetheless.

          23. Rose (usethebrainsgodgiveyou)May 27, 2011 at 5:15 PM

            That assumption would be similar to extrapolating information regarding people with Intellectual Disabilities by working with normal people.

            If autism is a way of being, then severe autism is a way of being with intellectual disabilities.

            But, I would like to know some things, many high functioning people with autism have the concomitant epilepsy, or movement disorders, or other biological/neurological manifestations that accompany autism so often. I would like to have a comparison of developmental trajectories, to see if it is just my imagination, when I compare my son as a young child and his language aquisition to severely autistic children of others who are going through the "same thing" at age 20. Do the physical malformations (now THAT's rude!) of severe autism mirror the p.m.'s (can't say it twice) of intellectually disabled persons who are not autistic? Or are they related to autism specifically.

            Then again, I have seen so many severely disabled autistics who look as though a missing chemical could complete a circuit, and speech would follow. They are gorgeous.

            I sometimes wish I had become a scientist instead of a teacher. Forgive me for being such a putz...but I do wonder about a lot of things.

            I'll try not to be anonymous Rose, if I can get this %$#@! thing to work.

          24. Rose (aka usethebrainsgodgiveyou)May 27, 2011 at 5:31 PM

            As a researcher and a Neurolgist,is your interest mostly related to psychology, or do you have an interest in biology? There must be some way to work with the kids who are more disabled. Just tell me to shut my trap, I'm not trying to be facetious, though.
            I know MRI's can be done under sedation, because my son had one at age 3 and I didn't think he'd wake up. Can you do EKG's? X-rays? I guess my fascination has always been biological. Too dumb to be a doctor, though, and couldn't take the responsibility.

            I have a thought about IQ, a strange assumption I ran across in my PMD classroom. If I can find the info, I'll get back with you. I don't know that it would add anything, but...

          25. I am the lawyer, father of a 15 year old son severely affected by autism, long time autism advocate in New Brunswick Canada and blogger whose concerns about the the Intellectual Disability issue in the DSM-5 you have dismissed.

            Your reference to my status as a lawyer is obviously irrelevant but insignificant. What is significant though is that you didn't back up with any persuasive argument your position that I misinterpreted the "offending" words. I gave the words their plain meaning and I also took note of the fact that those words are not used in the current DSM-IV description of autistic disorder the category into which most "autism spectrum" persons with Intellectual Disabilities will be found. The introduction of the additional words must be done for a reason.

            The reason on its face is to remove from consideration for an Autism Spectrum Disorder diagnosis anyone with intellectual disability and social communication deficits. You have re-characterized the wording by adding new wording not employed in the DSM5 diagnostic definition of Autism Spectrum Disorder. If the APA intended the interpretation you provide it could have used the wording you employed. It has not done that.

            Your characterization does not, even if accepted, make any sense. The new definition is supposed to facilitate the diagnostic process. Your suggestion would add a further requirement that, in cases of intellectual disability, any social and communication deficits be compared to persons of similar cognitive levels adding an additional complicating diagnostic task assuming it can even be done.

            Your argument is also deficient in light of the DSM-V move away from IQ as a sole determining factor for diagnosing intellectual disability. If ID diagnosis requires significant functional limitations in addition to IQ then it seems obvious that the immediate functional limitations will be in social and communication areas.

            As I pointed out in my original comment there is already a precedent in the DSM-IV for similar exclusionary wording. It is found in the criteria for Asperger's Disorder which states in Criterion E that "there is no clinically significant delay in cognitive development or in the development of age-appropriate self-help skills".

            The new Autism Spectrum Disorder expands, yet again, the diagnostic definition of autism on the high functioning end of the autism spectrum. It also uses exclusionary language with respect to intellectual disability only this time the exclusionary language is utilized with respect to the entire autism spectrum disorder and not just in relation to Aspergers Disorder.

            I would like to be wrong. I would like to think that your interpretation is correct. I am not convinced by your argument which is not backed up by any significant analysis of the defintions of autism and Aspergers in the DSM-IV and DSM-5.

            If you are sincere in your interpretation though I ask that you present to the APA text to clarify their choice of language in the definition of Autism Spectrum Disorder.


            Harold L Doherty
            Father of a severely autistic 15 year old son
            Fredericton, New Brunswick, Canada

          26. Harold

            Thanks for your comment. Like the APA I could have chosen better words!

            I agree with you that the proposed wording for ASD in DSM 5 could be interpreted as meaning “If you’ve got intellectual disability then you can’t have autism as well”.

            However, that’s not what I think the intended meaning is. My reasoning has nothing to do with the precise wording of DSM IV or DSM 5, but the fact that it wouldn't make any sense to exclude classic autism from autism spectrum disorder. The wording is ambiguous but I don't think we should impute some sinister motivation to the changes from DSM IV.

            I've just looked up the proposed revision for "Dyslexia" which reads as follows:

            "Difficulties in accuracy or fluency of reading that are not consistent with the person's chronological age, educational opportunities, or intellectual abilities."


            I think something analogous to this is what they are trying to convey in the autism spectrum guidelines.

            I'm sorry if you were offended by my reference to your profession. This was in response to Rose’s earlier comment that: “He's a lawyer, so he's into precise wording.” I actually think the APA could do worse than consult someone like you to avoid any further ambiguity. One only has to look at the confusion caused by the re-worded criteria for PDD-NOS in DSM IV to see how messy things can get. Perhaps they will. This is only the first draft after all.

            I hope this has cleared things up a bit.


          27. Interesting post. My son is currently diganosed with pdd-nos.
            Great blog by the way. Nice to find a fellow Australian blogging on the topic of Autism.

          28. usethebrainsgodgiveyou RoseMay 30, 2011 at 11:42 AM

            Not really...referring to the DSM5 diagnosis of dyslexia only reiterates the point. ID will once again be ID, with no reference to autism or dyslexia. The $50,000 a year for ABA for ID kids will diminish, I guess. Autism will ONLY be for the non-intellectually impaired.

            I guess then ID will include it's own umbrella that will once again take on the the total mix of people with any type of intellectual it did before Aspergers came in. But from my reckoning, there is autistic ID and regular ID. Autistic ID is regular ID on steroids. But there's the gift...the intensity will open the way more clearly for discovery. If the "experts" are just going to keep going over the same old theories, they are going to get the same old results.

            I can't imagine the reasoning for this. Wish I was behind the scenes where they were making sausauge, er, ah, science!! You yourself have said that truly ID kids are hard to work with. (I know, but they are far and away the MOST fascinating in my work.) I think the greatest reward would also lie there.

            It just screams inflammation/allergy/maladaptive metallurgical response to me, but I tend to see things biologically, and not psychologically. (PKU, Wilson's Disease, the bodies inability to chelate iron, copper, mercury naturally...yes, Acrydonia interests me, too. I have no shame.)

            I think it's a mistake to go there that way...just saying...

          29. I finally had a chance to watch that Michael Rutter video (the one downside of my lovely new laptop is that it doesn't do Youtube). The whole series of clips are fascinating. Here's the link again:


          30. Jon;
            A just published epidemiological paper that analyzed over 5,000 children in Finland comparing DSM-IV-tr (2000) to the APA's published DSM-V (2011) draft criteria. DSM-V draft criteria was found to be less sensitive than DSM-IV-tr with respect to Asperger Syndrome or high functioning autism.

            Not a good start and DSM-V draft criteria, and unless further revisions are made, it appears that many Asperger type cases may 'fall through the cracks'. Back to the drawing boards?


          31. Thanks RAJ. Very interesting. Lets hope the final version of DSM 5 takes all of these findings into account.

          32. Lets take a look at the offending phrase that Rose and Harold seem to object to:

            "Persistent deficits in social communication and social interaction across contexts, not accounted for by general developmental delays..."

            Harold thinks this means that those with general developmental delays will now be excluded. Thats not actually what the wording states. It states exactly that 'deficits...across contexts' etc.

            I interpret the wording to mean that if the deficits particular to autism can be better accounted for by a general developmental delay then that is where they should diagnostically be placed. If however the deficits particular to autism cannot be better attributed to developmental delay in a general sense then they will still be diagnosed as autistic.

            However, they may still have developmental delays entirely distinct from autism. Thus one person may have both autism and an intellectual disability. Plentu of autistic people have comorbid conditions (epilepsy etc) and plenty of people with other issues (Down Syndrome etc) have autism as a comorbidity. I see no reason to believe the DSM V will result in a different circumstance(s).

          33. usethebraingodgiveyou RoseMay 31, 2011 at 6:02 AM

            Michael Rutter talks too much and says too little. Just my "opinion". Then again, I'm probably a refrigerator mother.

            Gets too damn heavy carrying that thing on my back.

          34. Kev's comments about Downs Syndrome with co-occuring autism raises questions about the entire concepts of the meaning of 'genetics' and 'heritability'.

            First, Rutter's two-hit hypothesis has been demonstrated in Downs Syndrome with or without co-occurring autism. Ghaziuddin (1997, 2000) compared a group of Downs Syndrome children and their first degree relatives (parents and siblings) with or without co-occurring autism. In Downs Syndrome with co-occurring autism there was an excess of first degree relatives who met the description of broad autism features compared to first degree relatives in Downs Syndrome children without autism who did not. The Downs Syndrome mutation was not present in first degree relatives, parents and siblings, and the genetic influences underlying the broad autism phenotype appears to be separate, secondary and a background genetic effect to the neuroanatomical alterations associated with intellectual disability (ID) in Downs Syndrome. Downs Syndrome with co-occurring autism may not be inherited but paradoxically does strongly suggest the likelihood of a gene X gene synergistic etiology further obfuscating the concepts of 'genetics' and 'heritability' that are all too frequently used interchangeably.



            Second, twin studies in Down's Syndrome raises important questions about about the interpretation of classical twin studies which compares concordance rates in identical twins to concordance rates in fraternal twins then calculates a 'heritability estimate'

            E.F. Torrey in 1992 reviewed the literature and identified every case report of Down's Syndrome in twins. He found that 98% of identical twins were concordant for Down's Syndrome and 2% of fraternal twins were concordant for Down's Syndrome which if interpreted by classical twin study design would make Down's Syndrome, not autism, the most heritable of all the developmental disorders which is nonsensical since Down's Syndrome is not heritable at all.


          35. Jon;

            Most people interested in every aspect of autism cannot attend many conferences in autism such as the recent IMFAR Conference in San Diego.

            The Annual Autism Europe Conference is unique in that they make videos of every presentation avaialble online:


            The video presentations include almost every aspect of autism from neurobiology, genetics, diagnostic issues, treatments and more.

            The presentations in the videos are made by many of the most well known researchers in autism including Simon Baron-Cohen, Eric Fombonne, Sir Michael Rutter, Catherine Lord, Fred Volkmar and many many others.

            For those who can't afford to attend Autism Conferences the online videos made available by the Autism Europe Conference is a valuable resource for anyone, parents, families, researchers and science writers interested in current autism issues.

            IMFAR and other conferences should follow Autism Europes lead.

          36. Great article.. I like to know more about autism.. I am glad that I've found your site.. Thanks so much!

          37. usethebrainsgodgiveyou :)June 3, 2011 at 7:57 AM

            Dr. Brock...should you ever need to rid yourself of defective eye tracking equipment...come see me at raggette. Possibly my son could work on it, and we could use it for Paige, a profoundly disabled CP kid I taught who is of normal intelligence.

            Just sayin....can't afford the $5000, although it's come down half price since I taught her.

            Sorry to be such a pain. I'm outta here. Good luck with your studies.

            The skeptic's cynic, Rose

          38. Kev statements of belief are interesting but they do not in fact address the points I have raised in my comments. At best the kind of circular reasoning demonstrated in his comments will cause problems for diagnosing autism where the subject is intellectually disabled. The reference to ID deficits as possible exclusionary criteria does not exist in the current definition of Autistic Disorder or PDD-NOS.

          39. I am commenting as Anon because I do not know how to get my name (Bob) put up given the options available at the bottom. I have no URL but I do have a google account--will that put my name up? thanks for any help.

            Anyway, I do not see much in the above in reference to spontaneous imitation and mirror neurons. Compromised mirror neurons are a step back from genes and so may be a better way to look for potential problems arising in imitation abilities.
            Any thoughts from the amazing members of the audience to this blog?


          40. I am the parent of an autistic child in the UK. I recently read a book called ASD the enigman unlocked by an unknown author, someone called D Hatfield-Hall. You should read it, awsome,unbeleivable, shocking - it explains what we've all be looking for. I suspected it for years.

          41. The children that would not get a diagnosis of ASD because their Restricted repetitive behaviors were not as prevalent, will receive a diagnosis of "Social Communication Disorder". That is not in the DSM-IV; it is a new diagnosis that will be in the DSM-V. I'm sure that children who are diagnosed with "Social Communication Disorder" will be receiving speech&language therapy, as well as social skills therapy. Children already with a current diagnosis of PDD-NOS or Asperger's Syndrome will be rolled into the Autism Spectrum Disorder diagnosis. Because there is going to be a new condition recognized as Social Communication Disorder, these children that are not yet diagnosed as Asperger's and PDD-NOS will NOT be falling through the cracks, receiving no diagnosis and thus not getting any services.

          42. Reading some of the comments, and the last one in particular, compels me to respond. I taught in classrooms that provided special education services for 30 years. Over the years the 'qualifications' for receipt of services changed. They fluctuated according the state's education department's specifications. Of course these had to be in alignment with those of the federal government as well. Many of these issues are far more political and fiscal in nature that the actual needs of the population. It doesn't matter a whole lot what happens with DSM-V. The state institutions will define what services are made available according to the limitations set by that state's definitions.What happens is that the qualifying criteria will change for funding purposes, and when the child shows that he/she is performing to his/her capacity according to those guidelines, services are no longer provided-or- they no longer qualify for services under the new definition. The learning, social, emotional, communication,and mental problems are still there. Those children do not go away, only the support services do. Be careful here. We are dealing with the lives of human beings. History has already shown what happens with this kind of thing. The exclusionary definition of learning disabilities left the door open for many, many interpretations of the law when it came to who qualified for services. The medical definitions were one thing, the legal ones for providing services were another.

          43. I often wonder about how accurate diagnostic criteria for PDD-NOS really is. My son "R" was diagnosed with PDD-NOS at age 2 1/2. However, he is VERY social, VERY loving, and makes friends everywhere he goes. We have not mentioned his diagnoses to his current doctors (and never mentioned it to school officials). He received a diagnosis of ADHD at age 7 and has responded very well to stimulant medication. When he's on stimulants, he acts completely "normal". When he's off the meds we can see some of the autistic-type behaviors emerge (repetitive speech, comments that are totally off topic, extreme hyperactivity and some repetitive behaviors). He did well in public school through 2nd grade, but 3rd grade became too stressful. He's now been homeschooling for a year (just finishing 3rd grade) and is doing most school work at a 4th grade level and reading at a 7th grade level. He tested gifted and talented in public school in 2nd grade. He's a quirky kid for sure, but with medication, he acts like a "normal" and very intelligent almost 9yr old.

          44. Our younger son "L" was diagnosed with "borderline autism" at age 2 by ECI. What does that even mean? We don't know. What we do know is that now, at age 7 1/2, he is extremely intelligent. He is fascinated with outer space and astro-physics. His idol is Stephen Hawking. It takes many tries to get him to follow through on cleaning his room, but his understanding of space is beyond what I can comprehend. He skipped 1st grade and is currently making straight A's in 2nd, and the work is still too low-level for him. He is fascinated by math and says that he constantly has numbers going through his head. He's capable of adding/subtracting 30 digit or more numbers, multiplying and dividing, and is about to start 4th grade math at home. He doesn't display many "autistic" behaviors, but he does have staring spells after which he will say something "profound" about the universe or math. He doesn't make friends easily and is sometimes perceived as "weird" by other kids. He also has issues with anger management, is often too rough with animals, and has bouts of extreme hyperactivity. He is VERY disorganized and tends to be defiant. Is he on the autism spectrum or is he just a quirky genius? I have no idea, but the public schools can't meet his needs so he will be homeschooled starting next year. I suspect he will be taking a few college astronomy, physics, or math classes by age 12. Socially, I don't know that he will ever have a large circle of friends or be able to relate as well as he should to others. He should be able to function very well as an adult though.